The research program of the Laboratory of Neurophysiology may be defined broadly as concerned with the problems of cerebral localization in sensory and motor systems, with the anatomical substrates of these systems, with the interrelations of different systems and with the contributions of each level of the neuraxis to function and behavior. The program deals with the afferent mechanisms of touch, temperature, taste, hearing, vision, somatic motor system, and the hypothalamus and brain stem. The approach in general is comparative, employing a wide variety of vertebrates. The methods of electrical stimulation, ablation, evoked potential and single unit recordings are employed and computers are used for analysis of electrophysiological data and the simulation of unit behavior. Emphasis is placed on careful neurosurgical technique and its application in the placement of lesions, based on physiologically determined maps of cortical areas, for the study of neurological and behavioral alterations and for the study of thalamocortical relations and other anatomical connections. Several anatomical methods including autoradiography are now employed.